If you guys don't OWN a linkedin Group then you are missing out... Anyone can create a group on virtually any professional category. By creating the group you have the control on who joins. Also by being the group owner you are in the POWER position in the network. (nobody is going to mess with you). Just think... (for an example) if you are a lowly secretary at IBM you could create a IBM business group. If the CEO wanted to join the group they would have to be approved by the secretary. Long term...some of these groups are going to be huge. LInkedin Groups are free to join!
I actually ended up getting a new job from a contact intiated on LinkedIn. Almost doubled my pay! Great site IMHO.